Chip makers battle it out in the octa-core SoC arena

Several semiconductor companies introduced their ARM-based octa-core SoCs at the Mobile World Congress, and while this may be so, it will not be until they get slotted in mobile devices that the performance of these SoCs can be evaluated.

If there was any doubt about the potential for octa-core ARM-based processors, the flurry of announcements at MWC will put that to rest. Allwinner, MediaTek, and Qualcomm all announce 8-core SoCs for mobile devices. The new devices join octa-core solutions already available from MediaTek and Samsung.

First up is Allwinner, which has aggressively entered the mobile SoC market and quickly differentiated itself from the other Chinese vendors by going after mid-range solutions. Allwinner announced the 32bit UltraOcta A80 SoC featuring four ARM Cortex A7s plus four ARM Cortex A15s in ARM's big.LITTLE configuration. The A80 also features the PowerVR Series 6 GPU in what appears to be a dual-core configuration from Imagination.

Next is MediaTek with the introduction of the company's second 32bit octa-core SoC, the MT6595. The MT6595 also features the ARM big.LITTLE configuration, but features four ARM Cortex A7s combined with four ARM Cortex A17s, ARM's latest 32bit CPU and one particularly aimed at mobile applications. The MT6595 also features Imagination's PowerVR Series 6 GPU in a dual-core configuration plus all the wireless interfaces for a complete mobile SoC, including 802.11az (WiFi), GPS, Bluetooth, FM, ANT+, and full 4G LTE support in a single chip. Note that MediaTek previously announced the MT6592, which featured eight ARM Cortex A7s and the ARM Mali450 GPU. MediaTek also announced a quad-core 64bit MT6732 using ARM Cortex A53s.

Last but not least is a new and the only 64bit octa-core, the Snapdragon 615 from Qualcomm. The 615 utilises eight ARM Cortex A53s configured into two quad-core clusters. One cluster is optimised at the silicon-level and frequency for power and the other for performance. Qualcomm is also offering a quad-core version called the Snapdragon 610, which is a step up in performance from the previously announced Snapdragon 410. The 615 and 610 also feature Qualcomm's new Adreno 405 GPU. All of the new devices from Qualcomm are pin compatible and include Qualcomm's 4G LTE cellular modem.

These join the Samsung Exynos 5 Octa, which features four ARM Cortex A7s with four ARM Cortex A15s, similar to the new Allwinner device, but with the previous generation PowerVR Series 5 GPU from Imagination.

All of the new devices are capable of handling 4k/H.264 video encode and decode, and are being positioned for high-end mobile devices, as well as other consumer applications. Unlike the rush to 64bit with custom CPU cores, however, the rush to octa-core has all been around using standard synthesisable IP cores from ARM where SoC vendors can leverage the ARM big.LITTLE core configuration and/or rapid time to market.

Evaluating the different products on specs alone is rather challenging. According to ARM, the Cortex A17 used in the MediaTek MT6595 provides a 60 per cent performance boost over the Coretex A9, but there is not a direct comparison to the A15 because the two devices are aimed at different segments of the market and have different architectural features. In addition, the ARMv8 64bit architecture has significant enhancements over the ARMv7 32bit architectures, but it's not clear how a group of little 64bit cores will compare in performance to a group of big 32bit cores, especially when there are few 64bit applications available. If that weren't enough, each vendor has a different method of power gating the various CPU cores and different configurations for GPU cores.

Measuring the performance of the various SoCs will have to wait until the devices using these SoCs are available, which should be starting in the second half of 2014. However, in terms of network connectivity, which is often overlooked in most performance evaluations, MediaTek and Qualcomm have the clear advantage.